Bowmar 904-10-2

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After Bowmar entered the market in September 1971 with the first American-made pocket calculator, the 901B, design for newer models began. Launched in 1972 for office use, the type 904 desktop calculators was based on the previous 901B and 901D models; their CPUs was the same, their display became a large Burroughs’ Panaplex II gas-discharge tubes, and their keyboard was based on the same Klixon metal spring technology used in previous pocket calculators, but with a spring-loaded mechanism for greater press length. The clicking noise, which was amplified by the new structure, was suppressed using sound-absorbing sponges. In addition to the American market, it was also planned to conquer the European markets, so the transformer unit of these calculators could be switched to the usual european 220/230 V voltage. The machines could be used in fixed decimal point mode, which Texas Instruments chips would have made possible with pocket calculators, but this feature was not utilized in Bowmar’s ones, mainly for space-saving reasons, except for the Commodore Minuteman model.

The 904-8 model is an 8-digit, the 904-10 and its successor, the 904-10-2 are 10-digit models, with the same construction, except for their display.

In 1973, the Hungarian Híradástechnika Szövetkezet (Telecommunication Cooperative) in Budapest assembled some types from the current product range of Bowmar, so a smaller series of 904-10-2 was produced, which were marketed under type number A-100.

The 904 model, with almost unchanged interior, placed in a housing of different colors, was still in production for years, with newer and newer type designations (904xx, TX), according to the ever-changing numbering scheme.